As disclosed in Patent Document 1 (Japanese Unexamined Patent Publication No. 2005-55641), fillers for electronic devices can fill air gaps of display devices to improve visibility and durability and reduce thickness. The properties required for these fillers include heat resistance, adhesion, transparency, and the like, and recently the demand for high heat resistance is increasing.
As fillers, acrylic fillers and silicone fillers are widely used. Conventionally, acrylic fillers have an excellent adhesion and are low in cost, but there is a disadvantage that durability is deteriorated at high temperature and low temperature. Conventionally, silicone fillers have excellent heat resistance and chemical resistance, but there is a disadvantage that adhesion is deteriorated, tensile strength is weak, and the price is high. Therefore, it is necessary to develop fillers having excellent heat resistance and adhesion together.